A Short History of the Devil by Neil Mohammed

Horned gods were worshipped in Europe and the rest of the world from the dawn of humanity. They were always part of a pagan belief system, a polytheistic belief system, which accepted many gods. Tribal pagan belief systems still in existence share this characteristic: the tribes worship their tribal gods, and other gods mentioned by strangers are not evil, or non-existant, they are simply not their gods.

There were many ancient monotheistic religions such as Judaism, but again these were tribal religions, which had no urge to prosyletise, to "spread the word". Jehova was the god of the Jews, and they felt no need to persuade other tribes to worship him as well.

Christianity changed all that. It felt an overpowering need to make their one god the god of everybody else within range, and so they invented the missionary. But to do this it was necessary to discredit the old pagan gods, and in particular the goddess and the horned god.

Pagan pantheons never include gods of evil. Pagan gods are aspects of Nature, and in Nature there can be no evil; it exists only in the human imagination. They frequently include trickster gods, such as Loki, and gods can have a reputation for being unwise to be involved with, but not actual evil. Monotheistic religions, on the other hand, require a god of evil as an adversary of their god of good. Otherwise, why would you need Him? An obvious way to discredit the horned god and justify punishment of his worshippers is to say that he is, in fact, the god of evil in the new religion. And has been all along.

This did not happen all at once. For centuries Christianity existed alongside much older pagan beliefs all across Europe, and adapted to the people there and accomodated their beliefs as far as possible. The Celtic Christian Church in Dark Age Ireland is a typical example.